1. Field of the Invention
The present invention relates to a tensioner device for a wrapping connector driving device in an internal combustion engine for automatically applying a given tension force to an endless transmission belt extended between a driving wheel and a driven wheel supported on an engine body.
2. Description of the Prior Art
An internal combustion engine has been well known in which an endless transmission belt is extended between a driving wheel and a driven wheel, and an automatic adjuster is connected to a tensioner body pressed against the transmission belt to thereby always apply a given tensioer force to the transmission belt (Japanese Utility Model Application Laid-Open No. 202039/82).
In the above-described conventional tensioner device, a feed oil chamber of a hydraulic automatic adjuster is open to outside, and when it is operated, oil tends to partly leak outside. Therefore, if a belt type wrapping connector driving device is employed, there arises a problem that leaked oil may adhere to the transmission belt, resulting in an increase in slip of the transmission belt to deteriorate the transmission efficiency and quicken the deterioration of the transmission belt.
In order to overcome these inconveniences as noted above, the aforesaid hydraulic automatic adjuster has to be designed oil-tightly, and if a seal member such as an O-ring is provided at sliding parts between the cylinder and piston of the automatic adjuster, there poses problems that the relative sliding resistance thereof may be increased and the seal member may quickly be worn out and also that the sealing effect may become insufficient.
Furthermore, if a seal member is used as a seal between the cylinder and piston of the automatic adjuster, it is difficult to absorb a tension shock and a surplus tension force applied to the transmission belt during the operation of an internal combustion engine, giving rise to problems that the durability of the transmission belt may be affected disadvantageously, and the transmission efficiency may further be deteriorated.